1. Field of Invention
The present invention relates to a surface plating process. More particularly, the present invention relates to a process for forming an interface between a plated and a non-plated area.
2. Description of Related Art
Surface plating finds many applications in the manufacturing industry. Aside from providing the surface of a product with a metallic luster, the plated metallic layer also has the capacity to shield against electromagnetic interference (EMI). In general, plating can be categorized into electroplating and electroless plating. In the electroplating, a reduction-oxidation reaction is set up inside an electrolyte (a metallic salt solution) so that the metallic ions are reduced back to metal (for example, copper or nickel) and deposited on the surface of the plating material that also serves as a cathode. In the electroless plating, a reducing agent is applied to a surface with metallic ions so that the metallic ions are reduced to metal and deposited on the surface of a plating surface without the passage of an electric current. In other words, electroless plating can be considered as a chemical plating process. To plate the surface of a plastic product, an electroless plating process is performed to form a seeding layer over the surface so that a subsequent electroplating process can be applied to form a compact metallic layer.
In the conventional method of plating a metallic layer on the surface of a plastic product, a masking or an etching method is often used to define the plated region and the non-plated region. One method is to set up a mask over the non-plated regions before carrying out an electroplating operation. After the electroplating operation, the mask is removed. A second method is to perform an etching process so that the seeding layer over the non-plated region is removed. After performing an electroplating operation, any residual metallic layer over the non-plated region is removed. A third method is to perform a high-power laser etching process to remove the metallic layer over the non-plated region after an electroplating operation. A fourth method is to set up a mask over the plated region after an electroplating operation. Thereafter, an etching process is carried out to remove the metallic layer over the non-plated region before removing the mask layer.
All the aforementioned plating methods for forming a metallic layer over a plastic surface have some form of defect at the interface between a plated region and a non-plated region. In the first method, the cost of producing the mask is high and, consequently, leads to a high production cost. Moreover, the quality of the interface produced by the mask is typically poor. In the second method, not only is the cost of performing the etching process relatively high, but the etching process also roughens the surface of the non-plated region. Moreover, some residual etching solution may contaminate the surface of the plated region and hence lower the plating yield. In the third method, the energy produced by the high-power laser may damage the surface of the non-plated region or produce undesirable marking on the surface of the non-plated region. In the fourth method, the cost of producing the mask is high and the quality of the interface produced by the mask is typically poor just like the first method.